3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first argument is zero

*** 18,28 ****
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2011 by Delphix. All rights reserved.
   */
  
  /* Portions Copyright 2010 Robert Milkowski */
  
  #include <sys/zfs_context.h>
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright (c) 2012 by Delphix. All rights reserved.
   */
  
  /* Portions Copyright 2010 Robert Milkowski */
  
  #include <sys/zfs_context.h>
*** 1060,1070 ****
           */
          lrc->lrc_seq = ++zilog->zl_lr_seq; /* we are single threaded */
          lwb->lwb_nused += reclen + dlen;
          lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg);
          ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz);
!         ASSERT3U(P2PHASE(lwb->lwb_nused, sizeof (uint64_t)), ==, 0);
  
          return (lwb);
  }
  
  itx_t *
--- 1060,1070 ----
           */
          lrc->lrc_seq = ++zilog->zl_lr_seq; /* we are single threaded */
          lwb->lwb_nused += reclen + dlen;
          lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg);
          ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz);
!         ASSERT0(P2PHASE(lwb->lwb_nused, sizeof (uint64_t)));
  
          return (lwb);
  }
  
  itx_t *